UNESCO announced on January 20 that scientists have discovered a huge coral reef deep in the waters off Tahiti (Tahiti) in the South Pacific, which has not been affected by climate change and remains "pristine", the world's largest.
"It's like a work of art"
The newly discovered reef, which is about 3 kilometers long and 65 meters wide, was discovered by divers in November 2021 with special underwater equipment, and they studied the reef for 200 hours, including photography, measurement and sampling. These huge rose-shaped corals can each be up to two meters in diameter.
UNESCO calls it "one of the largest pristine reefs on record" and the discovery of this healthy reef in colder waters at depths of 30 to 65 meters is "highly unusual": this could indicate that there are more reefs deep in the ocean, that are in a safer state and are not affected by warming seawater.
Alexis Rosenfeld, a French photographer and founder of UNESCO partner 1 Ocean, said: "It was amazing to see the beautiful giant rose-shaped corals in the air. It's like a work of art. ”
"So far, we don't know as much about the deep sea as we know about the lunar surface," added AUDrey Azoulay, director-general of UNESCO, adding that only 20 percent of the world's seabed is mapped.
"Incredible"
"The discovery of this reef in such a pristine state is good news that could inspire future conservation efforts," said Laentitia Hedouin, a marine biologist at the French National Centre for Scientific Research in Moorea, French Polynesia. ”
Scientists say the discovery is "unbelievable." It is well known that most of the known coral reefs in the world are found at a depth of 25 meters. According to UNESCO, Tahitian reefs may indicate that there are more healthy coral areas in the "twilight zone" that are not drawn in the ocean.
Tahiti is the largest island in the French Polynesian archipelago and is located in the South Pacific. The four seasons are warm and spring-like, and the products are abundant. Residents call themselves "god's men," while foreigners see it as "the closest place to heaven."
Back in 2019, French Polynesia suffered a major bleaching event, but the newly discovered reef does not appear to have been significantly affected. Herden said: "These corals show no signs of stress or disease. ”
It is understood that bleaching occurs when healthy corals are stressed by soaring ocean temperatures, causing them to expel algae from tissues, leaving large amounts of albinos in the once-thriving ecosystem.
The threat of global warming
Starfish can also destroy them by eating corals. Scientists have placed temperature sensors in the area to analyze why corals appear to be unaffected by climate change and to monitor their population dynamics. Coral reefs, although only a small part of the seafloor, are home to at least a quarter of marine flora and fauna.
Last October, the Global Coral Reef Monitoring Network said that from 2009 to 2018, overfishing, seawater pollution and, more importantly, global warming had destroyed 14 percent of the world's coral reefs. The most affected are corals in South Asia and the Pacific, around the Arabian Peninsula and off the coast of Australia.
The oceans absorb more than 90 percent of the excess heat from greenhouse gas emissions, protecting the land surface, but creating large, persistent ocean heatwaves that push many coral species beyond their limits. In 1998, an bleaching event caused by warming seawater led to the extinction of 8% of corals.
Herden said Tonga's recent submarine volcanic eruption triggered a tsunami in the Pacific Ocean, but did not affect coral reefs near Tahiti. She hopes the study will help experts understand how coral reefs are resilient to the effects of climate change and human activities, and the role these deeper corals may play in marine ecosystems.
Nandu reporter Shi Minglei